It has long been desired to provide a long lasting system that automatically waters an area of land when the soil reaches a predetermined moisture level. The agricultural industry has attempted to devise numerous systems to achieve such a result.
An example of a precursor to the automatic watering system of the present invention is the use of moisture sensors such as gypsum moisture blocks. The gypsum is cast around a pair of stainless steel electrodes and buried in the soil. Wire leads are attached to the electrodes and protrude outward from the soil and can be attached to a marker for reference. Then, a person can attach a resistance meter to the wires to obtain a resistance measurement. The resistance reading translates directly to soil moisture. There are many shortcomings associated with such a system. The most obvious drawback is that this is not an automatic system. It requires human intervention to take the readings and take action based upon those readings. The moisture sensors of the above described conventional system must also be replaced every season because the gypsum dissolves and exposes the electrodes thereby leading to corrosion. Furthermore, gypsum blocks do not work well with all types of crops. Instead, the gypsum blocks can accurately work only with crops that are less water-sensitive, such as cotton and small grains. Moreover, the above described system does not provide an accurate measure of soil moisture over an extended period of time. The calibration of the gypsum block changes with time, thereby limiting the life of the block.
Automatic watering systems have also been attempted, but suffer from some of the same drawbacks as the manual systems. Some automatic systems have moisture sensors which must be changed out each season and that do not give accurate readings over an extended period of time. Other systems require a user to position the sensors in series or parallel only, as opposed to either configuration. It is desired to have an automatic watering system that is as flexible as possible. It is further desirable to have a system that provides an accurate measure of soil moisture and that can be used for multiple seasons without requiring the sensors to be replaced.
Another drawback of some conventional automatic systems is the inadequacy of the moisture controller that controls a solenoid water valve. Conventional moisture controllers have problems such as producing significant radio frequency interference in nearby areas, thereby causing problems with neighboring houses. Some conventional moisture controllers also have problems with oscillation of the water valve due to a lowering of the supply voltage. For example, once the solenoid valve is actuated, a supply voltage drop occurs which can cause the control to then turn off the valve, causing oscillation. Other exemplary conventional moisture controllers do not operate at the same voltage as the water valves which they control; or the moisture controllers require more current than the overload protection of the valve. This prevents the moisture controller from being connected directly to the valve. It is desired to have a moisture controller that can prevent oscillation of the valve and that can be positioned and connected to the valve itself.